Description
Return periodYear-ageYears and subtract recordedBirthYear for identityResidual.
Longitudinal ageing research links observations to people, waves, and sources. A person may appear in multiple records, so distinct-person coverage and record counts answer different questions and require explicit duplicate rules.
Return periodYear-ageYears and subtract recordedBirthYear for identityResidual.
When to use this tool
Use Cohort Age Period Birth Year Identity when you need a record-coverage or source-support diagnostic in ageing research.
How to use the tool and how it works
- Enter periodYear, ageYears, recordedBirthYear. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read impliedBirthYear, identityResidual. Use the output convention below.
Require nonnegative ageYears. Return periodYear-ageYears and subtract recordedBirthYear for identityResidual.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| periodYear | Period Year | Required. Finite number. |
| ageYears | Age Years | Required. Finite number; minimum 0. |
| recordedBirthYear | Recorded Birth Year | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| impliedBirthYear | Implied Birth Year | Required. Finite number. |
| identityResidual | Identity Residual | Required. Finite number. |
{
"input": {
"periodYear": 2026,
"ageYears": 70,
"recordedBirthYear": 1955
},
"output": {
"impliedBirthYear": 1956,
"identityResidual": 1
}
}Limitations and assumptions
- Age and period use the supplied year-coordinate convention rather than precise birthdays; the identity check does not verify records or identify separate age, period, and cohort effects.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Review the original study design, identifiers, and missing-data definitions. Use the full longitudinal dataset for inference rather than treating a local coverage flag as evidence of representativeness.
References
Similar or alternative tools
- Cohort Period Index Gap
Subtract cohortIndex from periodIndex using exact integer intermediates before numeric export.
- Pension Study Birth Cohort Index
Floor (birthYear-originYear)/cohortWidth for cohortIndex and return the corresponding lower year and excluded upper year.